While automatically assembling parts to a car body, a car body is usually conveyed by a conveyer to a working station and stopped at a predetermined position there. Thereafter, the position of the car body is detected by a position detector, such as a visual sensor, in order to adjust the position of the assembling jig based upon the detected results. Parts are then assembled to the car body.
Since complicated control operations are necessary, in the above-mentioned automatic assembling system, using expensive sensors such as visual sensors or the like, the cost of equipment is high.